JP2015040294A - Abrasive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an abrasive which can improve retentivity on an abrasive pad when performing polishing and can efficiently improve polishing characteristics even when a polishing object is chemically stable quartz glass.SOLUTION: Provided is an abrasive 1 comprising mixed powder or a solid solution having zinc oxide (ZnO) 11 included in abrasive grains 12. An average particle size of zinc oxide 11 is 10% or more and 60% or less relative to an average dispersion particle size of the abrasive grains 12.

Description

  The present invention relates to an abrasive for polishing an object to be polished.

  Conventionally, high-precision flatness and high polishing efficiency are required in polishing of glassy objects such as magnetic disk glass substrates and liquid crystal display glass substrates. When polishing such an object to be polished, the polishing object is generally held on a polishing platen while supplying the polishing slurry in which the abrasive is dispersed in water with the object being held in a holder or the like. Polishing is performed by pressing and rotating the surface to be polished of the object to be polished against the polishing surface of the polishing pad provided.

  Conventionally, as a polishing material for glass polishing such as a glass substrate for a magnetic disk or a glass substrate for a liquid crystal display, various materials such as ceria (cerium oxide), zirconia (zirconium oxide), iron oxide (bengara) and the like have been conventionally used. Material is used. In recent years, in order to improve polishing efficiency, glass polishing using an abrasive mainly composed of cerium oxide has been performed (see, for example, Patent Document 1). Since it is a rare earth (rare metal) and highly dependent on the specific country of origin, the use of alternative materials is required to reduce the amount used.

  In addition, as an alternative material for cerium, the present inventors have used metal oxides, non-oxides, metals or these oxides in abrasive grains mainly composed of oxides or double oxides of zirconium, silicon, or iron. By including the mixture, the inventors have invented an abrasive that can improve the retention on the polishing pad during polishing and improve the polishing efficiency (see, for example, Patent Document 2).

Japanese Patent Laid-Open No. 11-060282 JP2013-121649A

  However, in Patent Document 1 and Patent Document 2, when quartz glass that is extremely high purity and chemically stable is used as an object to be polished, the surface roughness is efficiently improved and the polishing efficiency is improved. There was a problem that it was difficult.

  The present invention has been made in view of the problems as described above, and improves the retention on the polishing pad during polishing, and the quartz glass in which the object to be polished is chemically stable. Even in such a case, an object is to provide an abrasive capable of efficiently improving the polishing characteristics.

  In order to achieve the above object, the abrasive according to claim 1 is an abrasive made of a mixed powder or a solid solution in which abrasive oxide grains contain zinc oxide (ZnO), and the zinc oxide is made of the zinc oxide. The average particle size is characterized by being 10% or more and 60% or less with respect to the average dispersed particle size of the abrasive grains.

  The abrasive according to claim 2 is characterized in that an average dispersed particle size of the abrasive grains is 0.3 μm or more and 2.0 μm or less.

  The abrasive according to claim 3 is an abrasive whose main component is an oxide or a double oxide of diamond, silicon carbide, zirconium, cerium, silicon, aluminum, chromium, or iron. .

  The abrasive according to claim 4 is characterized in that the pH is in the range of 4-10.

  The abrasive according to claim 5 is characterized in that the zinc oxide is contained in a ratio of 5 wt% or more and 45 wt% or less when the mass of the entire abrasive is 100 wt%.

  According to the abrasive of claim 1, zinc oxide (ZnO) contained in the abrasive grains is excellent in aggregating action, and the abrasive grains are agglomerated to accelerate the precipitation. Improves the retention performance on the pad and increases the number of abrasives (abrasive grains) that act on the polishing process, thus improving the polishing efficiency even for chemically stable quartz glass Can do. Moreover, since polishing efficiency can be improved, the usage-amount of the abrasive grain for abrasives can also be reduced and cost can also be reduced. Moreover, since cleaning after use is relatively easy and environmentally friendly, the burden on the polishing apparatus and the operator can be reduced.

  According to the abrasive according to claim 2, since the average dispersed particle size of the abrasive grains is 0.3 μm or more and 2.0 μm or less, the surface roughness can be improved efficiently.

  According to the abrasive according to claim 3, the abrasive grains for abrasive mainly comprise an oxide or a double oxide of diamond, silicon carbide or zirconium, cerium, silicon, aluminum, chromium or iron. Since it is an abrasive grain and zinc oxide has a lower hardness than these abrasive grains, it is possible to suppress the occurrence of scratches and scratches on the surface to be polished of the object to be polished during polishing.

  According to the abrasive of Claim 4, since pH is the range of 4-10, polishing efficiency can be improved more.

  According to the abrasive of claim 5, since zinc oxide is contained in a proportion of 5 wt% or more and 45 wt% or less when the total mass of the abrasive is 100 wt%, the polishing action of the abrasive grains for abrasive The polishing efficiency can be improved more efficiently without hindering the above.

It is a schematic explanatory drawing for demonstrating the effect | action by the abrasives which concern on this invention. It is a graph which shows the sedimentation characteristic of the polishing slurry using the abrasive | polishing material which concerns on this invention. It is a figure which shows the comparison of the sliding angle of the polishing slurry using the abrasive | polishing material which concerns on this invention.

Hereinafter, the abrasive according to the present invention will be described. The abrasive of the present invention comprises a mixed powder or a solid solution in which zinc oxide (ZnO) is contained in abrasive grains for abrasive. As abrasive grains for abrasives, for example, abrasive grains mainly composed of oxides or double oxides of diamond, silicon carbide or zirconium, cerium, silicon, aluminum, chromium or iron can be used. However, the present invention is not limited to this, and abrasive grains used for conventionally known glass polishing may be used. The oxides of zirconium, cerium, silicon, and iron are zirconia (ZrO ₂ ), ceria (CeO ₂ ), silica (SiO ₂ ), and iron oxide (FeO, Fe ₂ O ₃ , Fe ₃ O ₄ ), respectively. Examples of the zirconia double oxide include zirconium silicate. The average dispersed particle size of these abrasive grains for abrasives is 0.3 μm or more and 2.0 μm or less, and more preferably 0.7 μm or more and 1 in order to efficiently improve the surface roughness during polishing. .3 μm or less is used.

  The abrasive grains mainly composed of diamond, silicon carbide or zirconium, cerium, silicon, aluminum, chromium or iron oxides or double oxides are not particularly limited. For example, zirconia is the main component. As abrasive grains to be used, those containing about 80 to 85 wt% of zirconia manufactured by Universal Photonics and Ferro, which are generally commercially available, zirconia manufactured by Fujimi Incorporated and Daiichi Rare Element Chemical Industries, Ltd. Is about 95 wt%. Further, zirconium silicate or the like can be used as the abrasive grains mainly composed of a double oxide of zirconium. As the abrasive grains containing ceria as a main component, conventionally available abrasive grains containing 80 wt% or more of ceria as a main component can be used. As the abrasive grains containing silica as a main component, conventionally available abrasive grains containing 80 wt% or more of silica as a main component can be used. Moreover, as an abrasive grain which has iron oxide as a main component, the abrasive grain which contains 80 wt% or more which has iron oxide as a main component conventionally marketed generally can be used.

  Zinc oxide (ZnO) added to abrasive grains mainly composed of diamond, silicon carbide, zirconium, cerium, silicon, aluminum, chromium or iron oxide or double oxide is oxidized zinc (Zn). It has a specific gravity of 5.67 and a Mohs hardness of 4-5. As this zinc oxide, for example, one having an average particle size of 10% to 60%, more preferably 40% to 60%, with respect to the average dispersed particle size of the abrasive grains is used. In addition, since zinc oxide has a lower Mohs hardness than abrasive grains mainly composed of diamond, silicon carbide or zirconium, cerium, silicon, aluminum, chromium or iron oxides or double oxides, it is polished. In this case, it is possible to suppress the occurrence of scratches, scratches and the like on the polished surface of the object to be polished.

  In addition, zinc oxide retains without impairing the polishing action of abrasive grains mainly composed of diamond, silicon carbide or zirconium, cerium, silicon, aluminum, chromium or iron oxide or double oxide. In order to improve the weight of the polishing material, it is included in a ratio of 5 wt% or more and 45 wt% or less, more preferably 20 wt% or more and 40 wt% or less when the total mass of the abrasive is 100 wt%. As described above, in the abrasive of the present invention, zinc oxide having an excellent aggregating action is mainly composed of an oxide or a double oxide of diamond, silicon carbide, zirconium, cerium, silicon, aluminum, chromium or iron. By being contained in the abrasive grains, it is possible to improve the retention on the polishing pad by aggregating the abrasive grains and accelerating the precipitation of the abrasive grains. That is, as shown in FIG. 1, when the quartz glass substrate 3 that is a polishing object is polished while supplying the polishing slurry in which the abrasive 1 of the present invention is dispersed in water onto the polishing pad 2, By adsorbing the abrasive grains 12 with the zinc oxide 11 having excellent adsorptive properties and acting as a composite, the precipitation of the abrasive grains 12 can be accelerated, and the retention on the polishing pad 2 can be improved. Thereby, since the number of abrasives (abrasive grains) acting on the polishing process on the polishing pad 2 can be increased, the polishing efficiency can be improved.

  The average particle size of the abrasive of the present invention is 0.5 μm in consideration of the surface roughness at the time of polishing, the polishing efficiency, and the dispersibility of the polishing slurry when dispersed in a liquid such as water. It is preferably formed so as to have a thickness of 3.0 μm or less. Moreover, pH is adjusted to the range of 4-10, Preferably it is 6-8, More preferably, it is the range of 7-8 in order to improve the cohesiveness of an abrasive grain. That is, a slurry in which the zeta potentials of abrasive grains (for example, zirconium oxide abrasive grains: isoelectric point pH 6.7) as main abrasive grains and zinc oxide to be added (isoelectric point pH 9.4) have different signs. It is preferable to be in the region.

  The method for producing the abrasive of the present invention is not particularly limited. For example, the oxide or double oxide of diamond, silicon carbide, zirconium, cerium, silicon, aluminum, chromium, or iron is the main component. The mixed powder showing the same sedimentation characteristics can be obtained by mixing the abrasive grains to be added and zinc oxide as an additive in the intended blending (ratio), and subjecting the mixture to wet classification. At this time, if the mixed powder to be produced exceeds the above-mentioned average particle size, it may be adjusted by appropriately performing a pulverization treatment so that the average particle size is 0.5 μm or more and 3.0 μm or less. . In addition, an appropriate amount of zinc oxide is added to a polishing slurry in which abrasive grains mainly composed of oxides or double oxides of diamond, silicon carbide or zirconium, cerium, silicon, aluminum, chromium or iron are dispersed in water. Alternatively, the aggregating action of zinc oxide may be used. In addition, a conventionally known method may be applied.

  Hereinafter, examples of polishing using the abrasive of the present invention and a comparison with conventional abrasives will be described.

Example 1
In Example 1, as a polishing slurry in which the abrasive of the present invention was dispersed, zirconium oxide abrasive grains having an average dispersed particle diameter of 0.7 μm (manufactured by Universal Photonics): 3 wt%, zinc oxide having an average particle diameter of 0.3 μm: The quartz glass was polished using a polishing slurry of 1 wt%, water: 96 wt%, pH 7.33.

Regarding the polishing conditions, polishing was performed under the following conditions. Moreover, about the grinding | polishing result of Example 1 and Comparative Examples 1-3, what divided the polishing efficiency, surface roughness, and polishing efficiency 30 minutes after the start from grinding | polishing by surface roughness (P / R). It is shown in Table 1. Note that P / R is one of the indices indicating superiority or inferiority of the polishing characteristics, and the higher the value, the better the polishing characteristics.
(Polishing conditions)
Polishing device: MAT-BC15 (manufactured by MAT)
Polishing pad: KSP90 (manufactured by Kuju Electric)
Polishing pressure: 20 kPa
Polishing platen rotation speed: 60rpm
Work holder rotation speed: 60rpm
Slurry flow rate: 25 mL / min

(Comparative Example 1)
In Comparative Example 1, zirconium oxide abrasive grains (manufactured by Universal Photonics): a polishing slurry having a pH of 6.9 in which 3 wt% was dispersed in water: 97 wt% as a polishing material was used under the same polishing conditions as in Example 1. Glass was polished.

(Comparative Example 2)
In Comparative Example 2, the same polishing conditions as in Example 1 were used, using a polishing slurry having a pH of 7.01 in which zirconium oxide abrasive grains: 3 wt% and copper oxide (CuO): 1 wt% were dispersed in water: 96 wt% as an abrasive. The quartz glass was polished at

(Comparative Example 3)
In Comparative Example 3, polishing similar to that in Example 1 was performed using a polishing slurry having a pH of 5.56 in which zirconium oxide abrasive grains: 3 wt% and copper oxide (WO ₃ ): 1 wt% were dispersed in water: 96 wt% as an abrasive. The quartz glass was polished under the conditions.

  As shown in Table 1, in Example 1 in which quartz glass was polished using the abrasive of the present invention in which zinc oxide was added to zirconium oxide abrasive grains, Comparative Example 1 using only zirconium oxide abrasive grains was used. Also, the polishing efficiency is improved, and the polishing efficiency is improved as compared with Comparative Examples 2 and 3. The P / R showing the superiority or inferiority of the polishing characteristics shows the highest value, and it can be seen that this is effective for chemically stable quartz glass.

  FIG. 2 shows the sedimentation characteristics when each polishing slurry is measured using a photoelectric sensor PX-10 (manufactured by Keyence Corporation). As shown in FIG. The settling speed of the polishing slurry of Example 1 in which zinc oxide was added to the grains was about 30 times faster than Comparative Example 1 using only zirconium oxide abrasive grains. Compared with Examples 2 and 3, the sedimentation rate is high.

  3 shows zirconium oxide abrasive grains having an average particle diameter of 0.7 μm (made by Universal Photonics) of Example 1: 3 wt%, zinc oxide having an average particle diameter of 0.3 μm: 1 wt%, water: 96 wt%, pH 7 .3 and the zirconium oxide abrasive grains of Comparative Example 1: 3 wt% dispersed in water: 97 wt% pH 6.9 polishing slurry each having a liquid volume of 100 μl supplied to the polishing pad (KSP90) The measurement result of the corner is shown. As shown in FIG. 3, in Comparative Example 1, the polishing slurry already slipped from the polishing pad at a sliding angle of 43 °, whereas in Example 1 in which the abrasive of the present invention was dispersed, the polishing pad was still It can be seen that the polishing slurry stays on top and the sliding angle is large. In this way, when using a polishing material with zinc oxide added to the main abrasive grains, the polishing slurry is prevented from being removed from the polishing pad by the centrifugal force accompanying the rotation of the polishing pad during polishing. can do. That is, the retention of abrasive grains on the polishing pad is improved, and the number of abrasives (abrasive grains) acting on the polishing process can be increased, so that the polishing efficiency can be improved.

  Next, Table 2 shows the results of polishing quartz glass when the average particle diameter of zinc oxide added to the zirconium oxide abrasive grains is different from that of Example 1 as Comparative Examples 4 to 6. ing.

(Comparative Example 4)
In Comparative Example 4, a polishing slurry of zirconium oxide abrasive grains having an average dispersed particle diameter of 0.7 μm: 3 wt%, zinc oxide having an average particle diameter of 1.1 μm: 1 wt%, water: 96 wt%, pH 7.53 as an abrasive. The quartz glass was polished under the same polishing conditions as in Example 1.

(Comparative Example 5)
In Comparative Example 5, a polishing slurry of zirconium oxide abrasive grains having an average dispersed particle diameter of 0.7 μm: 3 wt%, zinc oxide having an average particle diameter of 0.6 μm: 1 wt%, water: 96 wt%, pH 7.55 as an abrasive. The quartz glass was polished under the same polishing conditions as in Example 1.

(Comparative Example 6)
In Comparative Example 6, a polishing slurry of zirconium oxide abrasive grains having an average dispersed particle diameter of 0.7 μm: 3 wt%, zinc oxide having an average particle diameter of 0.065 μm: 1 wt%, water: 96 wt%, pH 7.63 is used as an abrasive. The quartz glass was polished under the same polishing conditions as in Example 1.

  As shown in Table 2, Example 1 in which zinc oxide having a particle size about half of the average dispersed particle size of zirconium oxide abrasive particles as main abrasive particles was added was oxidized as in Comparative Example 4. When zinc oxide having a particle size larger than the average dispersed particle size of zirconium abrasive grains is added, when zinc oxide having a particle size similar to the average dispersed particle size of zirconium oxide abrasive particles is added as in Comparative Example 5 In addition, the polishing efficiency is greatly improved and the polishing characteristics are also improved as compared with the case where zinc oxide having a particle size of less than 1/10 of the average dispersed particle size of zirconium oxide abrasive grains is added as in Comparative Example 6. I understand that.

(Example 2)
Next, in Example 2, as a polishing slurry in which the abrasive of the present invention was dispersed, cerium oxide abrasive grains having an average dispersed particle diameter of 1.2 μm: 3 wt%, zinc oxide having an average particle diameter of 0.3 μm: 1 wt%, Water: Soda glass was polished under the same conditions as in Example 1 using a polishing slurry of 96 wt% and pH 7.7.

Example 3
In Example 3, as a polishing slurry in which the abrasive of the present invention is dispersed, cerium oxide abrasive grains having an average dispersed particle diameter of 1.2 μm: 3 wt%, zinc oxide having an average particle diameter of 0.6 m: 1 wt%, water: 96 wt. % Soda glass was polished under the same conditions as in Example 1 using a polishing slurry of pH 7.5.

(Comparative Example 7)
In Comparative Example 7, a polishing slurry having a pH of 6.9 in which 3 wt% of cerium oxide abrasive grains having an average dispersed particle diameter of 1.2 μm: dispersed in 97 wt% of water was used as an abrasive, and the polishing conditions were the same as in Example 1. The soda glass was polished.

  As shown in Table 3, in Examples 2 and 3 in which soda glass was polished using the abrasive of the present invention in which zinc oxide was added to cerium oxide abrasive grains, comparative examples using only cerium oxide abrasive grains were used. An improvement in polishing efficiency of 8% or more than 7 was observed.

Example 4
Next, in Example 4, as a polishing slurry in which the abrasive of the present invention is dispersed, cerium oxide abrasive grains having an average dispersed particle diameter of 1.2 μm: 3 wt%, zinc oxide having an average particle diameter of 0.3 μm: 1 wt%, Quartz glass was polished in place of soda glass, which is an object to be polished in Example 2, under the same conditions as in Example 2 using a polishing slurry of water: 96 wt% and pH 7.7.

(Example 5)
In Example 5, as a polishing slurry in which the abrasive of the present invention was dispersed, cerium oxide abrasive grains having an average dispersed particle diameter of 1.2 μm: 3 wt%, zinc oxide having an average particle diameter of 0.6 μm: 1 wt%, water: Quartz glass was polished under the same conditions as in Example 4 using a 96 wt%, pH 7.5 polishing slurry.

(Comparative Example 8)
In Comparative Example 8, the same polishing conditions as in Example 4 were used, using a polishing slurry having a pH of 6.9 in which 3 wt% of cerium oxide abrasive grains having an average dispersed particle diameter of 1.2 μm was dispersed in 97 wt% of water as an abrasive. The quartz glass was polished.

  As shown in Table 4, in Examples 4 and 5 in which the silica glass was polished using the abrasive of the present invention in which zinc oxide was added to cerium oxide abrasive grains, comparative examples using only cerium oxide abrasive grains were used. The polishing characteristics were significantly improved as compared to 8, especially in Example 5 using zinc oxide having a particle size about half the particle size of cerium oxide abrasive grains, an improvement in polishing efficiency of 40% or more was observed. . Moreover, in Example 4 and 5, the improvement of the remarkable grinding | polishing characteristic was acquired rather than the result which made soda glass of Example 2 and 3 grinding | polishing object, By adding zinc oxide with respect to a main abrasive grain, It can be seen that the polishing characteristics for the chemically stable quartz glass can be drastically improved.

  The abrasive according to the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the scope of the idea of the present invention.

  The abrasive according to the present invention can be used as an abrasive capable of improving the polishing efficiency when performing polishing using a polishing pad, and particularly in polishing of chemically stable quartz glass. It can be used effectively.

DESCRIPTION OF SYMBOLS 1 Abrasive material 11 Zinc oxide 12 Abrasive grain 2 Polishing pad 3 Quartz glass substrate

Claims (5)

An abrasive comprising a mixed powder or a solid solution containing zinc oxide (ZnO) in abrasive grains for an abrasive,
The average particle diameter of the zinc oxide is 10% or more and 60% or less with respect to the average dispersed particle diameter of the abrasive grains.   2. The abrasive according to claim 1, wherein an average dispersed particle size of the abrasive grains is 0.3 μm or more and 2.0 μm or less.   The abrasive grain for abrasives is an abrasive grain mainly composed of an oxide or a double oxide of diamond, silicon carbide, zirconium, cerium, silicon, aluminum, chromium, or iron. The abrasive according to 1 or 2.   The abrasive according to any one of claims 1 to 3, wherein the pH is in the range of 4 to 10.   The abrasive according to any one of claims 1 to 4, wherein the zinc oxide is contained in a proportion of 5 wt% or more and 45 wt% or less when the mass of the entire abrasive is 100 wt%.

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